Encapsulated MEMS device with humidity sensor

Abstract

The invention relates to a packaged MEMS device with a humidity sensor. A packaged MEMS device has a MEMS die of semiconductor material formed from a sensor body and a cover bonded to each other. The sensor body incorporates at least one MEMS component, and the cover carries a humidity sensor having a first set of electrodes and a second set of electrodes facing each other and capacitively coupled, the humidity sensor configured to provide a humidity signal. An encapsulation block of electrically insulating material surrounds the MEMS die and the humidity sensor.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to Italian Patent Application No. 102024000017911, filed on July 31, 2024, the contents of which are incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field

[0003] This disclosure relates to a microelectromechanical system (MEMS) device with a packaged humidity sensor. For example, the following description relates to inertial sensors such as gyroscopes and accelerometers, but is not limited thereto. Background Technology

[0004] As is well known, MEMS devices, especially those that realize inertial sensors such as gyroscopes and accelerometers, are typically encapsulated in a housing of insulating material to protect them from the external environment and to provide them with mechanical protection and electrical insulation.

[0005] The housing can be manufactured using different techniques. For example, inertial sensors are typically encapsulated using substrate grid array (LGA) packages made from molded resin blocks. This type of encapsulation is very common because it is inexpensive, easy to manufacture, and in most cases provides reasonable protection.

[0006] However, this technology cannot guarantee absolute impermeability to water droplets.

[0007] Therefore, in the presence of high humidity or worse, exposure to liquid, droplets can easily penetrate the outer shell.

[0008] This is disadvantageous because humidity can cause deformation of the housing (creating a mechanical stress state on the sensor) and the MEMS sensor itself, as can be seen by comparison. Figure 1 and Figure 2 As shown, Figure 1 and Figure 2 A cross-section through the packaged MEMS device 1 is schematically shown.

[0009] In detail, Figure 1 and Figure 2 The packaged MEMS device 1 shown includes: a support 2, such as a plastic substrate; a first die 3, which integrates signal processing circuitry, such as an ASIC (Application-Specific Integrated Circuit), hereinafter also referred to as ASIC die 3, attached to the support 2; a second die 4, which is attached to the first die 3, integrates a microelectromechanical system (MEMS), and hereinafter also referred to as MEMS die 4; and a package block 5, such as resin, surrounding the exposed upper surfaces of the first die, the second dies 3 and 4, and the support 2.

[0010] In particular, Figure 1 The encapsulated MEMS device 1 is shown in an undeformed state; Figure 2 The function of the water droplet 8 is shown. The water droplet 8 penetrates the encapsulation block 5 and causes deformation of the encapsulation block 5 and the underlying structure (support 2, first die and second die 3, 4).

[0011] In particular, stress induced on MEMS die 4 and deformation of the same MEMS die 4 may cause errors in the output signal of MEMS die 4, such as drift in reference values, such as the zero rate level (ZRL) value of the gyroscope or the zero gravity offset (ZGO) value of the accelerometer, which negatively affects sensor performance.

[0012] To address this issue, it has been proposed to associate humidity sensors with MEMS devices.

[0013] However, current commercial humidity sensors are large and incompatible with the size of current MEMS devices. For example, for comparison, a typical commercial sensor can be several centimeters in size to be compared with the millimeter size of MEMS devices. Therefore, current humidity sensors cannot be integrated into the same housing as MEMS dies.

[0014] The purpose of this disclosure is to provide a MEMS device incorporating a humidity sensor in a package. Summary of the Invention

[0015] According to this disclosure, a packaged MEMS device with a humidity sensor is provided, a method for calibrating the packaged MEMS device, and a method for compensating the output signal of the packaged MEMS device.

[0016] In one embodiment, this disclosure provides a packaged MEMS device comprising a MEMS die of semiconductor material, the die being incorporated into a sensor body and a bonded cap. The cap carries a humidity sensor having first and second sets of electrodes arranged facing each other and capacitively coupled to provide a humidity signal. The electrodes may be configured as intersecting metallic electrodes, and each set includes at least one electrode. An encapsulation block of electrically insulating material surrounds the MEMS die and the humidity sensor, and in some embodiments, the encapsulation block is configured such that the volume ratio of the encapsulation block to the total device volume satisfies 0.3. <V r / V tot <0.5. In some embodiments, for example, a humidity-sensitive layer comprising polyimide covers the humidity sensor and extends between the sensor and the package block. In other embodiments, the device also includes a processing die with an integrated processing unit, an electrode assembly connected to the processing unit via sensor pads, interconnections established via wire coupling, and the processing unit may be incorporated into a calibration unit for acquiring and compensating signals.

[0017] In another embodiment, this disclosure provides a method for calibrating a packaged MEMS device. The method includes providing a packaged MEMS device having a MEMS die, a humidity sensor with paired electrode groups, and a surrounding encapsulation block; introducing the device into an environment with a preset humidity level; and gradually changing the humidity level in the environment. The method further includes capacitively measuring the humidity change between the electrode groups while acquiring an output signal from the MEMS die, generating a correlation between the acquired output signal and the measured humidity change, and storing the correlation for subsequent compensation of the output signal during device operation. In some embodiments, the method includes keeping the device free from external acceleration other than gravity and utilizing a resin encapsulation block with a humidity-sensitive layer.

[0018] In another embodiment, this disclosure provides a method for calibrating multiple packaged MEMS devices. In this method, multiple devices (each including a MEMS die, a humidity sensor, and a package block) are introduced into an environment with a controlled humidity level. The humidity level is gradually changed while acquiring output signals from the MEMS die and corresponding humidity signals from the sensor. The method also includes interpolating the acquired signals across the multiple devices to obtain an average trend and storing the correlation between the interpolated output signals and the humidity signals. The method adapts to variations in humidity-displacement correlation due to manufacturing tolerances, wherein the interpolation includes calculating an average value between simultaneously acquired samples and the humidity change achieved through the gradual introduction of water droplets.

[0019] In another embodiment, this disclosure provides a method for compensating the output signal of a packaged MEMS device. The method includes providing the device, acquiring an output signal from a sensor body during operation, and simultaneously acquiring a humidity signal from a humidity sensor. The output signal is then compensated based on the humidity signal using previously stored correlation, wherein the humidity acquisition may involve detecting capacitance changes between groups of electrodes. These and other features are described herein. Attached Figure Description

[0020] To better understand this disclosure, embodiments thereof are now described with reference to the accompanying drawings, which are purely non-limiting examples, in which:

[0021] Figure 1 This is a schematic cross-sectional view of a pre-existing packaged MEMS device without deformation.

[0022] Figure 2 yes Figure 1 A schematic cross-sectional view of a pre-existing encapsulated MEMS device in a deformed state;

[0023] Figure 3This is a top perspective view of the packaged MEMS device, where the package is shown as a ghost image;

[0024] Figure 4 yes Figure 3 A cross-sectional view of a packaged MEMS device;

[0025] Figure 5 This is a cross-sectional view of the packaged MEMS device;

[0026] Figures 6 to 10 A graph showing the amount relative to the packaged MEMS device during the test steps is shown.

[0027] Figure 11 This is a schematic cross-sectional view of a packaged MEMS device in the presence of humidity and with a compensation unit.

[0028] Figure 12 This is a flowchart of the characterization steps for packaged MEMS devices;

[0029] Figure 13 and Figure 14 A graph showing the amount used to compensate for the drift of the measured quantity due to humidity, relative to the packaged MEMS device, is presented; and

[0030] Figure 15 This is a flowchart of the compensation steps for packaged MEMS devices. Detailed Implementation

[0031] The following description refers to the arrangement shown; therefore, expressions such as “above,” “below,” “upper,” “lower,” “right,” and “left” are related to the accompanying drawings and should not be interpreted in a restrictive manner.

[0032] Figure 3 and Figure 4 Microelectromechanical systems (MEMS) device 20 is shown.

[0033] MEMS device 20 includes: a support 22, such as a plastic substrate; a first die 23 of semiconductor material (such as silicon) for integrating signal processing circuitry, such as an ASIC (Application-Specific Integrated Circuit), hereinafter also simply referred to as ASIC die 23; a second die 24 of semiconductor material (such as silicon) for integrating MEMS die 24; a humidity sensor 30 formed above MEMS die 24; and an encapsulation block 25 made of an electrically insulating material such as resin (in... Figure 3 (shown as dashed lines in the middle).

[0034] The encapsulation block 25 surrounds the first and second dies 23, 24 and the humidity sensor 30, and covers the exposed upper surface of the support 22.

[0035] Specifically, the MEMS device 20 is housed in a substrate grid array (LGA) package.

[0036] In detail, the ASIC die 23 is attached to the support 22 and forms a processing unit that cooperates with the MEMS die 24 to perform tasks conceived for the MEMS device 20; for example, it receives signals related to the displacement of movable portions of the MEMS die 24 and processes them to obtain externally provided position, velocity, and acceleration information. Therefore, in the following text, the term "displacement" means "change in a measured quantity" or "the output of the MEMS die" (e.g., acceleration in the case of an accelerometer, angular velocity in the case of a gyroscope).

[0037] MEMS die 24 is attached to ASIC die 23 and includes sensor body 31 and cover 32.

[0038] The sensor body 31 is formed from the first wafer and integrates one or more inertial sensors, such as a gyroscope and an accelerometer with one or more axes, such as... Figure 4 The sensor body 31 is schematically shown in the diagram. In particular, in a manner not shown but known to those skilled in the art, the sensor body 31 includes a fixed portion integrated with the MEMS die 24, a movable portion subjected to displacement in the presence of external acceleration, and a detection structure configured to generate a corresponding displacement signal.

[0039] The cover 32 is typically formed from a second wafer different from the first wafer and is bonded to the sensor body 31; for example, it can be bonded at the wafer level or in a manner known per se after the MEMS die 24 has been cut.

[0040] Cover 32 may also have one or more cavities positioned above a corresponding sensor integrated in sensor body 31; cavities ( Figure 4 and Figure 5 28) can be set to a controlled pressure below atmospheric pressure and / or contain a specific gas. In the case of multiple chambers, they can be at different pressures.

[0041] Cover 32 can be electrically coupled to the block potential of MEMS die 24.

[0042] A humidity sensor 30 is formed on the cover 32 and is capacitive, consisting of electrodes of a conductive material (typically a metal such as aluminum) facing each other.

[0043] In detail, the humidity sensor 30 includes a first set of electrodes 33 coupled to a first sensor pad 34 and a second set of electrodes 35 coupled to a second sensor pad 36.

[0044] Each group of electrodes 33 and 35 may include one or more electrodes.

[0045] In particular, in the illustrated embodiment, the first group of electrodes 33 includes a plurality of first electrodes 38, and the second group of electrodes 35 includes a plurality of second electrodes 39, wherein the first electrodes 38 and the second electrodes 39 intersect each other.

[0046] For example, the first and second electrodes 38 and 39 can be formed of equal metal strips separated from each other by a gap, and the mutual capacitive coupling of the gaps can be detected by the ASIC die 23.

[0047] Specifically, in an area of ​​3×3mm 2 In the case of the MEMS die 24, the first and second electrodes 38 and 39 can have an elongated rectangular shape with a length of 2.5 mm, a width between 10 μm and 20 μm, and a gap of 5-10 μm. In this way, approximately 80 strips (80 electrodes between the first and second electrodes 38 and 39) are obtained.

[0048] In addition, Figure 3 and Figure 4 In the case of the cross-rectangular electrode configuration shown, the first arm 40 extends laterally to the first electrode 38 and is coupled to one end of the electrode; it is also coupled to the first sensor pad 34 at its end.

[0049] The second arm 41 extends laterally to the second electrode 39 and is coupled to one end of the electrode; it is also coupled to the second sensor pad 36 at its end.

[0050] The first and second sensor pads 34 and 36 are respectively coupled to the first ASIC pad 42 and the second ASIC pad 43 on the ASIC die 23.

[0051] Specifically, in the illustrated embodiment, sensor pads 34, 36 are indirectly coupled to corresponding ASIC pads 42, 43.

[0052] Specifically: the first sensor pad 34 is coupled to the first MEMS pad 46 formed on the upper surface of the sensor body 31 in the recessed area of ​​the cover 32, and the first MEMS pad 46 is coupled to the first ASIC pad 42; the second sensor pad 36 is coupled to the second MEMS pad 48 formed on the upper surface of the sensor body 31, and the second MEMS pad 48 is coupled to the second ASIC pad 43.

[0053] The coupling between sensor pads 34 and 36 and MEMS pads 46 and 48, and between MEMS pads 46 and 48 and ASIC pads 42 and 43, occurs through wire 50.

[0054] Figure 3It is also shown that additional MEMS pads 51 are coupled to corresponding additional ASIC pads 52 arranged on the ASIC die 23 via wires 50.

[0055] Furthermore, a first insulating layer 55 extends on the surface of the support 22; a first bonding layer 56 (e.g., a "die attachment" layer) extends between the first insulating layer 55 and the ASIC die 23; a second bonding layer 58 (e.g., a "die attachment" layer) extends between the ASIC die 23 and the MEMS die 24; a second insulating layer 59 ( Figure 3 Not shown in the image, but... Figure 4 (As can be seen in the image) it extends above the MEMS die 24, between the latter and the humidity sensor 30. The second insulating layer 59 is, for example, silicon oxide.

[0056] The humidity sensor 30 can be directly covered by the encapsulation block 25, such as Figure 4 As shown, or it can be covered by a humidity-sensitive layer, such as Figure 5 As shown.

[0057] In detail, Figure 5 It shows having Figure 4 The general structure of the MEMS device 20 is that of the MEMS device 120 (therefore common elements are indicated by the same reference numerals), wherein the humidity-sensitive layer 121 covers the humidity sensor 30, leaving exposed sensor pads 34, 36 (wherein in Figure 5 The second sensor pad 36 is shown only in dashed lines.

[0058] The humidity-sensitive layer 121 can be, for example, polyimide, with a thickness between 1 μm and 20 μm.

[0059] Figure 4 and Figure 5 The diagram shows a capacitance, represented by capacitor 60, coupled between the first and second electrodes 38, 39, and a capacitance penetrating from the outside of the MEMS devices 20, 120 and encapsulated by package block 25 and (for...) Figure 5 The presence of water droplets 61 absorbed by the humidity-sensitive layer 121 in the MEMS device 120.

[0060] exist Figure 4 and Figure 5 In the middle, the second insulating layer 59 is also visible, and the wires 50, MEMS 48, and ASIC pads 43 are indicated by dashed lines.

[0061] In addition, Figure 4 and Figure 5 In the example, the sensor body 31 of the MEMS die 24 integrates a gyroscope G and an accelerometer XL.

[0062] MEMS devices 20 and 120 are formed according to conventional MEMS manufacturing techniques; specifically, before or after cutting ASIC 23 and MEMS die 24, a second insulating layer 59 is deposited on the surface of cover 32, and a humidity sensor 30 is formed by depositing and defining a metal layer by photolithography, thereby forming first and second arms 40 and 41, first and second electrodes 38 and 39, and first and second sensor pads 34 and 36.

[0063] Then, possibly after forming the humidity-sensitive layer 121, wires 50 are formed to connect to the outside (not shown), and a molded encapsulation block 25 is formed.

[0064] In MEMS devices 20 and 120, they can absorb water droplets 61 when exposed to moisture. For example, the applicant's research has shown that resins commonly used for encapsulation can absorb up to 14% of their weight in water.

[0065] Similarly, the polyimide of the humidity-sensitive layer 121 has relatively high absorption properties.

[0066] When water droplets 61 seep into the encapsulation block 25 (and possibly into the humidity-sensitive layer 121), they cause a change in the dielectric constant εr of the layers (25, 121) inserted between the first set of electrodes 33 and the second set of electrodes 35, thereby changing the capacitance of the humidity sensor 30.

[0067] Therefore, the capacitance change experienced by the humidity sensor 30 can be used as a measure of humidity.

[0068] On the other hand, the presence of humidity in MEMS devices 20 and 120 can cause deformation of the same MEMS device 20, which may affect the reliability of the measurements performed.

[0069] There is a correlation between the existing humidity level (which can be measured by humidity sensor 30) and the deformation experienced; therefore, this correlation can be used to compensate for the measurements obtained by MEMS devices 20, 120.

[0070] Note that in some cases, the change in capacitance of the humidity sensor 30 is approximately proportional to the amount of water absorbed.

[0071] To this end, the test MEMS device, which is formed as MEMS device 20, has been introduced into a test environment in which a controlled humidity level has been generated and increases over time.

[0072] Under these conditions, the humidity trends detected at three points on the cover 32 and the corresponding displacements at three points on the sensor die 31 below the three points where the relative humidity Hr has been extracted have been simulated, as follows: Figure 6 (This shows the normalized time t) normThe curves of relative humidity Hr as a function of Hr are denoted as H1, H2, H3) and Figure 7 (The relative deformation measures Dr are denoted as D1, D2, D3) are shown.

[0073] These simulations have been repeated on multiple MEMS devices 20 and 120, and it has been demonstrated that there is a significant correlation between the signal measured by the humidity sensor 30 and the deformation of the MEMS device 20 when the humidity time constant (τh) and the device deformation time constant (τdef) are approximately similar.

[0074] Further research also shows that when the volume of the encapsulation block 25 of the MEMS devices 20, 120 (and possibly the humidity-sensitive layer 121) is included between approximately 30% and 50% of the total volume of the MEMS devices 20, 120, a similar trend in humidity time constant and deformation is obtained, i.e., the volume of the encapsulation block 25 is expressed as V r And the total volume of MEMS devices 20 and 120 is expressed as V. tot , which is:

[0075] 0.3 <V r / V tot <0.5 (1).

[0076] In fact, it has been seen that when the ratio V r / V tot Below 30%, the humidity signal measured by the humidity sensor 30 reaches a steady state very quickly before the MEMS device 20 deforms. See [link to relevant documentation]. Figure 8 This behavior is explained by the rapid flow of water from the top of the MEMS device 20 through the encapsulation block 25 to the humidity sensor 30, which immediately saturates it.

[0077] Furthermore, it has been observed that when the volume V of the encapsulation block 25... r Greater than the total volume V tot At 50%, the humidity signal measured by humidity sensor 30 follows the deformation change with a delay, see Figure 9 This behavior has been explained as being caused by droplets penetrating from the side of the MEMS device 20 rather than from the top where the humidity sensor 30 is located, thus the latter records the increase in humidity with a delay relative to the amount of droplets that penetrate the encapsulation block 25 and cause deformation.

[0078] In both cases, when the package block 25 is too small or too large compared to the size of the MEMS devices 20 and 120, the humidity measurement cannot accurately and timely represent the deformation, and therefore is not a reliable indicator that can be used for compensation, at least under certain operating conditions.

[0079] Conversely, within the range defined by relation (1), the applicant's research has shown that the average displacement measured as a function of humidity exhibits an approximately linear trend, such as Figure 10 As shown, where Def N H represents the normalized deformation. N Normalized humidity, expressed in any unit.

[0080] Under these conditions, drift of the measurement signals provided by the MEMS die 24 can be reliably compensated, such as the angular velocity value measured by the gyroscope G and / or the acceleration measured by the accelerometer XL.

[0081] Figure 11 The MEMS device 20 is schematically shown, deformed due to the presence of a water droplet (still indicated by 61). Humidity information (humidity signal H) is available via the humidity sensor 30. out The compensation portion 70 formed in the ASIC die 23 is provided.

[0082] The compensation section 70 also receives measurement results (measurement signal D) from an inertial sensor implemented in the MEMS die 24. out And compensation based on humidity signal H out The measured values ​​are described in detail below.

[0083] It should be noted that the humidity signal H out Instead of directly representing the existing humidity value, it measures the capacitance change between electrode groups 38 and 39 as described above; however, since this is uniquely related to humidity, as mentioned above, the term "humidity signal H" will be used in the following text. out "" indicates the humidity signal, which is uniquely related to the measured humidity and can be directly used for compensation, as discussed in detail below.

[0084] The applicant's research also shows that, due to the manufacturing tolerances of MEMS die 24 and / or the differences in mounting parameters between dies 23, 24 and support 22 and / or other factors, individual MEMS devices 20, 120 exhibit similar but not entirely consistent trends in terms of humidity-displacement correlation.

[0085] In order to allow the MEMS devices 20, 120 to operate reliably under all operating conditions, according to one aspect of this disclosure, an initial calibration procedure is performed on a series of MEMS devices 20 at the assembly batch level during the final test step.

[0086] For details, see Figure 12 The calibration process is performed by introducing multiple MEMS devices 20, 120 into a controlled humidity environment, gradually introducing water droplets into the controlled humidity environment to achieve a gradual and controlled increase in humidity level, box 80.

[0087] During the calibration process, the MEMS device 20 is kept without external acceleration (other than gravity) for measuring, for example, the zero rate level (ZRL) value of a gyroscope or the zero gravity offset (ZGO) value of an accelerometer.

[0088] During the humidity increase step, a calibration system (not shown, typically an external calibration device coupled to ASIC die 23) acquires the measured values ​​D of the MEMS devices 20 and 120 under test. out Box 82; Perform the operation on the acquired measurement value D out Interpolation, box 84; Obtain humidity information (humidity signal H) provided by the humidity sensor 30 of each MEMS device under test 20. out ), box 86; and execute humidity signal H out Interpolation, box 87.

[0089] For example, in block 82, the calibration system (not shown) samples the measurement signal D. out (its curve over time is in) Figure 13 (Shown for illustration purposes) and in block 86, humidity signals H generated by each humidity sensor 30 are sampled simultaneously. out (its curve over time is also...) Figure 14 (This is shown for illustrative purposes only).

[0090] It should be noted that the measurement signal D sampled and acquired by the calibration system (not shown) out This indicates the output of MEMS die 24, which has not yet been processed by the corresponding ASIC die 23.

[0091] Furthermore, in box 84, the measurement signal D sampled at the same time in different MEMS devices 20 and 120 under test is... out Interpolation is performed to obtain the average trend of families 20 and 120 of the tested MEMS devices, for example... Figure 14 As shown (measured by interpolation D) fam (The curve).

[0092] For example, interpolation can include calculating the measurement signal D obtained at the same time. out The average value between samples, or other appropriate type of interpolation.

[0093] Similarly, in box 86, the humidity signal H is acquired. out The corresponding sample, and in box 87, the interpolated humidity value H is calculated. fam ( Figure 15 ).

[0094] Measurement signal D out and the corresponding humidity signal Hout The sample acquisition and interpolation steps (boxes 82-87) are performed for a predetermined time, for example, whenever the acquired sample has significant variability, or for a predetermined time, such as several hours.

[0095] At the end of steps 82-87, the calibration system (not shown) creates the interpolated value D of the measurement. fam and the interpolated humidity value H fam The correlation between them is associated with relative values ​​(box 88), and then the correlation is stored (box 90), for example, in a table in the ASIC die 23 of the MEMS devices 20 and 120 under test.

[0096] The interpolated value D fam This can then be used as a correction factor for measurements performed during the real-time operation of each MEMS device 20, 120, such as ​ The flowchart is shown.

[0097] Specifically, during real-time operation, in each individual MEMS device 20, 120, the compensation section 70 acquires real-time measured values ​​DMEMS, box 100 from the die 24 according to the desired operating mode; and acquires the humidity signal H provided by the humidity sensor 30. out The corresponding value, box 102; in box 104, based on the acquired humidity signal H out The compensation value D stored at the same location fam Compensation is performed on the real-time measurement value DMEMS that was just acquired to obtain a compensation value DMEMS,comp; and, possibly after the compensation signal is further processed by the ASIC die 23, the compensation value DMEMS,comp obtained therefrom is sent to the outside of MEMS devices 20, 120, box 106, according to a predetermined process.

[0098] The MEMS devices, calibration methods, and operating methods described in this article have many advantages.

[0099] The humidity sensor 30 can be formed directly on the cover 32 of the MEMS die 24 using established microfabrication techniques, thus enabling it to be formed in a cost-effective and reliable manner.

[0100] The integrated manufacturing of the humidity sensor 30 within the MEMS devices 20 and 120 allows for a simplified design, which also facilitates the possibility of real-time performance compensation.

[0101] MEMS devices exhibit high sensitivity due to the maximized capacity achievable via the humidity sensor 30 formed directly on the cover, particularly when a drop of moisture remains on the electrode, and also due to the small gap between electrodes 38 and 39 (which can be achieved through photolithography).

[0102] By simply modifying the photolithographic mask defining electrode groups 33 and 35, the patterning of electrodes 38 and 39 is highly customizable due to the high flexibility of the available geometry.

[0103] The sensitivity of the humidity sensor can be easily adapted to MEMS applications / sensors implemented in MEMS die 24, thereby increasing the adaptability of MEMS devices to user / customer needs.

[0104] Finally, it is clear that modifications and variations may be made to the packaged MEMS devices, calibration methods, and operating methods described and illustrated herein without departing from the scope of the invention as defined in the appended claims.

[0105] For example, support member 22 may be absent and / or the type of package may be different, such as QFN type with different substrates.

[0106] As mentioned above, the number, shape, and size of electrodes 38 and 39 can vary.

[0107] During the calibration step (box 80), the humidity value H can be checked on a single device 20, 120. out The acquisition of.

Claims

1. A packaged MEMS device, comprising: A MEMS die made of semiconductor material includes a sensor body and a cap bonded together, wherein the sensor body is incorporated into at least one MEMS component; A humidity sensor, extending over the cover and including a first set of electrodes and a second set of electrodes, the first set of electrodes and the second set of electrodes facing each other and capacitively coupled, the humidity sensor being configured to provide a humidity signal; as well as An encapsulation block of electrically insulating material surrounds the MEMS die and the humidity sensor. The first group of electrodes and the second group of electrodes each include at least one electrode.

2. The packaged MEMS device according to claim 1, wherein the first group of electrodes and the second group of electrodes each include a plurality of intersecting electrodes.

3. The packaged MEMS device according to claim 1, wherein the first set of electrodes and the second set of electrodes are made of metal.

4. The packaged MEMS device according to claim 1 further includes a humidity-sensitive layer covering the humidity sensor and extending between the humidity sensor and the package block.

5. The encapsulated MEMS device according to claim 4, wherein the encapsulation block comprises resin and the humidity-sensitive layer comprises polyimide.

6. The packaged MEMS device according to claim 1, wherein the volume ratio V r / V tot The following relationship must be satisfied: 0.3 <V r / V tot <0.5, Where V r V is the volume of the encapsulation block, and V tot It is the total volume of the packaged MEMS device.

7. The packaged MEMS device of claim 1 further includes a processing die with an integrated processing unit, wherein the sensor body is bonded to the processing die and the first set of electrodes and the second set of electrodes are connected to the processing unit.

8. The packaged MEMS device of claim 7, wherein the first set of electrodes and the second set of electrodes are each coupled to a corresponding sensor pad disposed on the cover, the processing die includes a processor pad, and the sensor pad is coupled to the processor pad of the processing die.

9. The packaged MEMS device of claim 8, wherein the sensor pad is coupled to a corresponding MEMS pad disposed on the sensor body, the processing die includes an ASIC pad, and the MEMS pad is coupled to the ASIC pad, wherein the coupling between the sensor pad, the MEMS pad and the ASIC pad is wire coupling.

10. The packaged MEMS device of claim 7, wherein the processing unit includes a calibration unit, wherein the calibration unit includes: Components used to acquire MEMS signals from the MEMS die; Components for acquiring humidity signals from the humidity sensor; as well as A component used to compensate the MEMS signal based on the humidity signal.

11. The packaged MEMS device according to claim 1, wherein the MEMS component is an inertial sensor.

12. A method for calibrating packaged MEMS devices, comprising: A packaged MEMS device is provided, the packaged MEMS device comprising a MEMS die formed of a semiconductor material, a humidity sensor extending on a cover of the MEMS die, and a package block surrounding the MEMS die and the humidity sensor. Introduce the packaged MEMS device into an environment with a humidity level; Gradually change the humidity level in the environment; The humidity change between the first and second sets of electrodes of the humidity sensor is capacitively measured while the humidity level is gradually changed. The output signal is obtained from the MEMS die of the packaged MEMS device while the humidity level is gradually changed. Generate the correlation between the acquired output signal and the measured humidity change; as well as The correlation is stored to compensate for the output signal during operation of the packaged MEMS device.

13. The method of claim 12, wherein the humidity sensor comprises: The first set of electrodes and the second set of electrodes are intersected and capacitively coupled to detect humidity changes.

14. The method of claim 12, further comprising: During the calibration, the packaged MEMS device is kept free from external accelerations other than gravity.

15. The method of claim 12, wherein the encapsulation block comprises resin, and the humidity sensor is covered by a humidity-sensitive layer comprising polyimide.

16. The method of claim 12, wherein the correlation occurs when the humidity time constant and the equipment deformation time constant are approximately similar.

17. The method of claim 12, wherein the correlation between the output signal and the measured humidity change is stored in a table within the processing unit of the packaged MEMS device.

18. A method for calibrating multiple packaged MEMS devices, the method comprising: Multiple MEMS devices are provided, each MEMS device including a MEMS die of semiconductor material, a humidity sensor extending on the MEMS die, and a package block surrounding the MEMS die and the humidity sensor; Introduce the plurality of MEMS devices into an environment with controlled humidity levels; Gradually change the humidity level in the environment; The output signal is acquired from the MEMS die of the plurality of MEMS devices while the humidity level is gradually changed; Humidity signals are acquired from the humidity sensors of the plurality of MEMS devices while the humidity level is gradually changed; Interpolate the output signal and the humidity signal to obtain an average trend for the plurality of MEMS devices; and The correlation between the interpolated output signal and the interpolated humidity signal is stored.

19. The method of claim 18, wherein each MEMS device includes a humidity sensor formed on a cap of the MEMS die, the cap being bonded to a sensor body of the MEMS die.

20. The method of claim 18, wherein the plurality of MEMS devices exhibit similar but not entirely consistent trends in humidity-displacement correlation due to manufacturing tolerances.

21. The method of claim 18, wherein the interpolation comprises calculating an average value between samples of the output signal acquired at the same time.

22. The method of claim 18, wherein gradually changing the humidity level comprises gradually introducing water droplets to produce a gradual and controlled increase in the humidity level.

23. The method of claim 18, wherein each MEMS device comprises having a relationship satisfying 0.

3. <V r / V tot Volume ratio V <0.5 r / V tot The encapsulation block, where V r V is the volume of the encapsulation block and tot It is the total volume of the MEMS device.

24. A method for compensating the output signal of a packaged MEMS device, the method comprising: A packaged MEMS device is provided, the packaged MEMS device comprising a MEMS die of semiconductor material, a humidity sensor extending on the MEMS die, and a package block surrounding the MEMS die and the humidity sensor; During operation of the packaged MEMS device, an output signal is acquired from the sensor body of the MEMS die; A humidity signal is acquired from the humidity sensor during operation of the packaged MEMS device; as well as The output signal is compensated based on the humidity signal using the stored correlation between the output signal and the humidity signal.

25. The method of claim 24, wherein acquiring the humidity signal comprises: The capacitance change between the first set of electrodes and the second set of electrodes of the humidity sensor in the packaged MEMS device is detected.

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